Axial-flow fluid machines



Oct. 27, 1959 L. HAwoRTH ETAL 2,910,269

AxIAL-FLow FLUID MACHINES Filed Dec. s1, 195e llllllllm United States.Paw/H2O "we o AXIAL-FLOW FLUD MACHINES Application December 3'1, 1956,Serial: o. 631,3@

Claims priority, application Great Britain January 13, 1956v s Claims.(ci. ass-49) This invention comprises improvementsin or'- relating toaxial-flow fluid machines, such as, forexample, axialow compressors. andturbines of gas-turbine engines.

This inventionA has for an object to provide a construction ofaxial-flow fluid machine in which difficulties experienced with knownmulti-stage machines due toz distortion and relative thermal expansionare avoided.

'According to the present invention,- amultistag'e axialflow fluidmachine comprisesV rotor means` including a plurality of axially-spacedrows of'rotor blades; and a stator structure enclosing. the rotor meansand comprising a main casing, and. a plurality of axially-spaced rows ofstator blades or vanes, there being one row of said' stator blades orvanes just upstream ofeaclh row' of said rotor blades,- the. statorblades being provided at their radially-outer ends with platformstofornr pai-t'sof the wall ofthe' workinguid annulus of the' machinearound the, stator blades ori varies,` each said platformlbeingvv siip-Aported'i'frorn the main casing, andthe platforms of'adjacentJ rows ofsaid stator blades or vanas-'having aligned axial extensions whichtogethernalfordrlan annular stator shroud: encircling the: tips of therow -of rotor blades iri-l termediate they adjacent. rows of statorbladesl or varies.- By faligned?v is meant. that the extensions ofadjaeer'it`A rows" of stator'bla-des have parts at substantially the'sarne Iradialv distance from theraxis` of rotation of thev rotor jmeans,.which thus co-operate to afford said shroud;

Heretoforie it; has been the practice toy provide an annular shroud ofsubstantially the same axial dimension as the rotor blades, whichencircles the rotorv bladesand is formedin a small number of arcuatepieces; say'six; with such an arrangement not only are diicult-iesexperienced in design in order to allow for thermal expansion but it hasbeen found thattheseV pieces are liable to distortion inV operation ofthe machine. These diniculties are. avoided by the vconstruction of thepresent invention.` l Y v j The invention is applicable both tomachines' whereof the rotor blades have integral' shrouds at their:tips,l and to machines whereof' the rotor blades are not provided withintegral shrouds,

According to a preferred feature of the invention, the rotor bladeslhave" integral tip' shrouds, Vthe axial extensions of the platforms atthe radially-outer ends of the stator blades are radially offset fromthe radially-inner surfaces of the platforms, thereby to provideachannel into which the integral tip shrouds of rotor blades extend, andthe integral tip shrouds are arranged to co-operate with the axialextensions of the platforms'to provide gas seals to prevent excessiveflow of working uid around the tips of the rotor blades. In thepreferred arrangement the integral vtip shrouds have on their outersurfaces axially-spaced ribs which have radial surfaces, and'there areprovided radial surfaces on the axial extensions of the varies, whichhave for gassealing purposes small axial clearances from the radialsurfaces on the axiallyspaced ribs, all other clearances between the tipshrouds 2,910,269 et..V 27,. 1959 and the axial extensions beingsubstantially gieat'i' said small laxial clearances` 'Y one embodimenter this inventiit linee vbe dei scribed' Y'with reference to 'theaceornpflying' drawing, which shovvs in axial' section part 'of anaxial-now i'l'tisttifgetureiiie. Y

The turbine comprises the rowsY offiot'o" blades 10; 11, meunted aft ttpm-,ries er esifesponaing iot'oi dises; andi a stator v'structui'eincluding a rc'asliii'g 13v andE tlirer ws' f izle guide varies 14,15,116", the ravis et gti-ide: vases 14, 15,- 1eV Being fes'peetiveryjjtupstream of the rows ef the' iotereldes 10,11, 122. L

VThe guide vanes have both inner and outer bladepl forms 14a, 14b;,15a,15b; 16a,`16b, and the ilir blade p'latfoit'sy 142i; 15a', 16a of each;row aie 'secured rigidly tegetlieiin annuliyassjetiibiy: by Suitablestrutture. lThe outer blade?pllatter-"ni"S1421,Y 15b, 16h` of each roware'fre frein one another.Y Y y n n l l The high-pressurel nozzle guidevane's 174' 'have' oat'er platforms-146 fixed axially ancircumf'erentitrlly with respect to'tle casing 13 but left `free1`tadial-ly'. For this'- pu'rposa the casing 1131 is provided outsidevthe roteir blades 1'# iivitliaj radially-inwardly-projectiiig annular'.rib 17 frn'ed with a"inwardlyfacing annular` 'clianne'l'x 8f, andtheblade` platforms 14b` are provided along their downstream edges withaxial extensions 19frw'hicl`1'telriii'-l than 19t-intr zsiiieetiitg withSlight clearance-andeeieg'rdiauy onset from the inner' initiates` oftheplatforms i425; 15b te pif-avide tf channel 23a receivingtip siiftids221 ein theA Bla roaj'ffne'A radially'{it'tjrneri surfaces fL tl'e 'iexten' r9; areY snapt-: 1 teY affetti" at' parer radial' planesnrffa'cles 19t; which; in' epe-tation df the machine' havef-'axial,clearances froinf corresponding ra'li'al siii"- fties'zs siraaiaiiyspaeed iatiiauy oiitwatdiy'feiteiiditfg l jfofprovidegais-seals1i tiiiggtiie new afwerkinginiidi aroiidtlietitiistiretidsl--w t t Thea-varies" 1s;- 16'fre'1'ocatediti tite s'in'gr'sfifi's'innar ways. Y Thus` etten van@ 1s; lsa's on itsfpitfriii 15b-eirsbtadjaeent its upstream and dewnstieaa edges' hooked'fom'tion's2517281 29j 3( )`"whi"cli engager'espectively; in axially-ratingeliminar' ehnnels 31332; 33; 34", theF @nati-nels seing frniedrespectively iiittie radial ri 17.'Y and tnreefrtheif ribes-'5, 36; 37'providea any off tite-'easing 132 T efpiatfqrms `155,155ar'ethuslcated?'r`-z`1`dially. The ri-bs" If, 35;, 36and` 37varLe' alsoiprl' vided withradially-inwardly-projecting dogs 38 co-operating with dogs 39 on theplatforms 15b, 16b to locate them circumferentially. The platforms 15bare also l0- cated axially .by axially extending ring members 40, 41extending toward each other between the ribs 35, 36 and abutting radialflanges 42 on axial extensions 43 of the trapped between the rib 37 anda ring 50.

` The blades 11 have tip shrouds 24 and stator shrouding for these rotorblades is provided in amanner similar to that described for the blades10, by the axial extensions 43 of the platforms 15bA and axially-alignedcooperating extensions 44 on the upstream edges of the 'edf on theVouter Sartenes ef tnetip sii-ferias i Y, `amazes platforms 16b, theextensions 43 being shaped Vto alford plane surfaces l25 on ribs 26 suchas to afford gas seals to prevent excessive leakage of gas around thetip shroudsZ4. ky I It will be seen that the platforms 14b, 15b, 161: ofthe guide vanes are spaced radially fromthecasing 13 and cooling air isfed into this space from between the casing 13 and the nozzle dischargechutes leading from the flame tubes of the gas turbine engine to thehigh-pressure nozzle guide vanes 14. The air passes through the ribs 17,35 and 36 by means of drillings 45, 46, 47, therein and also throughcut-away portions on the hooked formations 28 and 29, and throughdrillings 48 in ring member 40. The air passes into the working fluidchannel through the small clearances between the platforms 14h, 15b and16b.

:We claim:

l. A multistage axial-dow fluid machine comprising rotor means includingaxially-spaced first and second rows of rotor blades and a statorstructure enclosing the rotor means which stator structure comprises `amain casing having internally thereof a series of axially-spacedinwardly-projecting circumferential ribs, artirst row of guide vanesupstream of said first row of rotor blades, a second row of guide vanesin flow series between*` said first and second rows of rotor blades,each of said guide vanes having an inner platform and an outer platform,means rigidly securing the inner platforms of the first row of guidevanes together in annular assembly, means rigidly securing the innerplatforms 4of the secondl row vof guide vanes together in annularassembly, each of the outer platforms of the first row of guide vaneshaving an axial downstream extension projecting downstreamtherefromaxially part way over the outer endsof the first4 row'of rotor bladesand, at the downstream end of said downstream extension a radial flange,one ofv said ribs of fthe main casing having an inwardlyfacing annularchannel engaged by saidradial` flanges to locate the first row of guidevanes axially in the casing and also having a downstream-facing annularchannel, means locating the first row of guide vanes circumferentiallyin themain casing, each of the outer platforms of the second row ofguide vanes having an axial upstream extension projecting upstreamtherefrom axiallyl part way over the outer ends ofthe first row of rotorblades and terminating adjacent the downstream ends of said downstreamextensions of the first row of guide x/anes, each of the outer platformsof the second row of guide vanes y.also having radiallyoutwardly-projecting hooked formations adjacent both its 'Y' outwardlyprojecting flanges, and a pair of ring members, planeA radial surfaces24 which havel clearances fromY upstream edge and its'downstream edge,the hooked for-` mations adjacent the upstream edges engaging saiddownstream-facing annular channel of said one rib,- a-second of saidribs of the main casing havinga downstreamfacing annular channel engagedby said hooked formations adjacentthe downstream edges ofthe outerplat-k forms, lsaid outer platforms of the second rowv of guide vanesand one of said ribs also having interengaging'dogs locatingthese guidevanes circumferentially in the casing, and each of said outer platformsof the second l,row of guide vanes having at their downstream edgesradially- .one oneach of the upstream and downstream sides of theradially outwardly projecting flanges, each of said ring members axiallyabutting by one end the radiallyoutwardly projecting flanges and by theother end said main casing to locate the second row of guide vanesaxially in the main casing.

2. A multi-stage axial-How uid machine according to claim 1, comprisinga third row of guide vanes downstream of said second row of rotorblades, which guide vanes have inner and outer platforms, means rigidlysecuringthe inner platforms of the third row of guide vanes together inannular assembly, each outer platform of the third row of guide vaneshaving at its upstream and downstream edges radially outwardlyprojecting hooked formations, a third of said ribs and a fourth of saidribs each having a downstream-facing annular chan nel engagedrespectively by the hooked formations at the upstream edges of theplatforms and the hooked formations at the downstream edges of theplatforms, means maintaining said hooked formations in the annularchannels, and interengaging dogs on said ribs and the outer platforms ofthe third row of guide vanes to locate them circumferentially on themain casing, downstream axial extensions of the outer platforms of thesecond row guide vanes axially projecting part way over the second rowof rotor blades, and upstream axial extensions of the outer platforms ofthe third row guide vanes projecting axially upstream and terminatingadjacent the downstream edge of the'downstream axial extensions of thesecond row guide vanes. l3. A multi-stage axial-flow ud machineaccording to claim 2, wherein said first and second rows of rotor bladeshave integral tip ,shrouds at their outer ends, the tip shrouds havingaxially-spaced radially outwardly projecting ribs which have at theirouter ends upstreamfacing radial surfaces, wherein said axial downstreamextensions of the outer platforms of the first and second rows of guidevanes and the axial upstream extensions of the outer platforms of thesecond and third rows of guide vanes are radially offset outwardly fromthe inner surfaces of the outer platforms to form channels receiving thetip shrouds of the rotor blades, and wherein the axial downstreamextensions have each a pair of axiallyspaced downstream-facing radialsurfaces having small axial clearance from the upstream yfacing radialsurfaces of the ribs on the tip shrouds to provide gas seals, theremaining portions of the tip shrouds having a substantially greaterclearance from the stator structure than s aid small axial clearance.

I References Cited in the file of this patent UNITED STATESYPACI`EN'-1`S 911,616 Roth -i Feb. 9, 1909 1,482,031 Parsons Ian. 29,1924 2,314,289 Salisbury 1 Mar. 16, 1943 2,488,875 Money -v Nov. 22,1949

Y FOREIGN PATENTS 200,055

l, Australia Nov. 4, 1955

